2 * Copyright (C) 1984-2007 Mark Nudelman
4 * You may distribute under the terms of either the GNU General Public
5 * License or the Less License, as specified in the README file.
7 * For more information about less, or for information on how to
8 * contact the author, see the README file.
13 * Operating system dependent routines.
15 * Most of the stuff in here is based on Unix, but an attempt
16 * has been made to make things work on other operating systems.
17 * This will sometimes result in a loss of functionality, unless
18 * someone rewrites code specifically for the new operating system.
20 * The makefile provides defines to decide whether various
21 * Unix features are present.
38 #define time_type time_t
40 #define time_type long
44 * BSD setjmp() saves (and longjmp() restores) the signal mask.
45 * This costs a system call or two per setjmp(), so if possible we clear the
46 * signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead.
47 * On other systems, setjmp() doesn't affect the signal mask and so
48 * _setjmp() does not exist; we just use setjmp().
50 #if HAVE__SETJMP && HAVE_SIGSETMASK
51 #define SET_JUMP _setjmp
52 #define LONG_JUMP _longjmp
54 #define SET_JUMP setjmp
55 #define LONG_JUMP longjmp
60 static jmp_buf read_label;
65 * Like read() system call, but is deliberately interruptible.
66 * A call to intread() from a signal handler will interrupt
67 * any pending iread().
78 #if MSDOS_COMPILER==WIN32C
82 #if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC
94 if (SET_JUMP(read_label))
97 * We jumped here from intread.
104 sigprocmask(SIG_SETMASK, &mask, NULL);
120 #if MSDOS_COMPILER==DJGPPC
124 * Don't try reading from a TTY until a character is
125 * available, because that makes some background programs
126 * believe DOS is busy in a way that prevents those
127 * programs from working while "less" waits.
132 FD_SET(fd, &readfds);
133 if (select(fd+1, &readfds, 0, 0, 0) == -1)
137 n = read(fd, buf, len);
140 * This is a kludge to workaround a problem on some systems
141 * where terminating a remote tty connection causes read() to
142 * start returning 0 forever, instead of -1.
145 extern int ignore_eoi;
148 static int consecutive_nulls = 0;
152 consecutive_nulls = 0;
153 if (consecutive_nulls > 20)
163 * Certain values of errno indicate we should just retry the read.
165 #if MUST_DEFINE_ERRNO
183 * Interrupt a pending iread().
188 LONG_JUMP(read_label, 1);
192 * Return the current time.
208 * Local version of strerror, if not available from the system.
216 extern char *sys_errlist[];
220 return sys_errlist[err];
221 sprintf(buf, "Error %d", err);
224 return ("cannot open");
230 * errno_message: Return an error message based on the value of "errno".
233 errno_message(filename)
240 #if MUST_DEFINE_ERRNO
247 len = strlen(filename) + strlen(p) + 3;
248 m = (char *) ecalloc(len, sizeof(char));
249 SNPRINTF2(m, len, "%s: %s", filename, p);
254 * Return the ratio of two POSITIONS, as a percentage.
255 * {{ Assumes a POSITION is a long int. }}
261 POSITION num100 = num * 100;
263 if (num100 / 100 == num)
264 return (num100 / den);
266 return (num / (den / 100));
270 * Return the specified percentage of a POSITION.
273 percent_pos(pos, percent, fraction)
278 /* Change percent (parts per 100) to perden (parts per NUM_FRAC_DENOM). */
279 long perden = (percent * (NUM_FRAC_DENOM / 100)) + (fraction / 100);
284 temp = pos * perden; /* This might overflow. */
285 if (temp / perden == pos)
287 return (temp / NUM_FRAC_DENOM);
289 /* Above calculation overflows;
290 * use a method that is less precise but won't overflow. */
291 return (perden * (pos / NUM_FRAC_DENOM));
296 * strchr is used by regexp.c.
303 for ( ; *s != '\0'; s++)
314 memcpy(dst, src, len)
319 char *dstp = (char *) dst;
320 char *srcp = (char *) src;
323 for (i = 0; i < len; i++)
332 * This implements an ANSI-style intercept setup for Microware C 3.2
335 os9_signal(type, handler)
337 RETSIGTYPE (*handler)();
350 if (_gs_opt(f, &sgbuf) < 0)
352 return (sgbuf.sg_class == 0);